The general preparation of silver nanowires (10-200 aspect ratio) is known. See, for example, Angew. Chem. Int. Ed. 2009, 48, 60, Y. Xia, Y. Xiong, B. Lim, S. E. Skrabalak, which is hereby incorporated by reference in its entirety. Such preparations typically employ Fe2+ or Cu2+ ions to “catalyze” the wire formation over other morphologies. The controlled preparation of silver nanowires having desired lengths and widths, however, is not known. For example, the Fe2+ produces a wide variety of lengths or thicknesses and the Cu2+ produces wires that are too thick for many applications.
When iron or copper are used, they are typically provided as the metal halide salts FeCl2 or CuCl2. See, for example, B. Wiley et al., Nano Letters, 2004, 4, 1733-1739 and K. E. Korte et al., J. Mats. Chem., 2008, 18, 437. Other metal halide salts have been used in nanowire synthesis. See, for example, J. Jiu, K. Murai, D. Kim, K. Kim, K. Suganuma, Mat. Chem. & Phys., 2009, 114, 333, which refers to NaCl, CoCl2, CuCl2, NiCl2 and ZnCl2, and S. Nandikonda, “Microwave Assisted Synthesis of Silver Nanorods,” M.S. Thesis, Auburn University, Auburn, Ala., USA, Aug. 9, 2010, which refers to NaCl, KCl, MgCl2, CaCl2, MnCl2, CuCl2, and FeCl3. Use of KBr has been disclosed in, for example, D. Chen et al., J. Mater. Sci.: Mater. Electron., 2011, 22(1), 6-13; L. Hu et al., ACS Nano, 2010, 4(5), 2955-2963; and C. Chen et al, Nanotechnology, 2006, 17, 3933. Use of NaBr has been disclosed in, for example, L. Zhou et al., Appl. Phys. Letters, 2009, 94, 153102. See also S. Murali et al., Langmuir, 2010, 26(13), 11176-83; Z. C. Li et al., Micro & Nano Letters, 2011, 6(2), 90-93; and B. J. Wiley et al., Langmuir, 2005, 21, 8077.
Japanese patent application publication 2009-155674 discloses use of SnCl4. U.S. patent application publication 2010/0148132 discloses use of NaCl, KCl, CaCl2, MgCl2, and ZnCl2. U.S. patent application publications 2008/0210052 and 2011/0048170 disclose use of quaternary ammonium chlorides.